Menstrie Meeting 2007

We again held our popular all day meeting at the Scout Hall, Menstrie (near Stirling) on 19th May for model building, demonstrations and a general chat. We also held our annual special race/competition. This year it was a "Reversing Vehicle" competition. See the Competition Rules page for more details.

Menstrie Challenge - Report

The Challenge was fought out at the annual Menstrie Constructor's Day and attracted eleven entries in all. Of these two were
exactly the same design (although realised with slightly different parts) and came from David Lawrence in the USA. Another two entries were from the
same person (Chris Shute) but were radically different from each other.

Aim:

To produce a vehicle which will automatically reverse as many times as possible between a pair of obstacles 4 feet apart

Rules:-

The motive power shall be a post Second World War Magic clockwork motor.

All parts of the model must be standard numbered Meccano or Meccano replica parts and appear in the ISM Inclusive Parts list.

The Magic clockwork motor shall be an integral part of the moving model.

The maximum size of the vehicle to be width 9 inches and length 12 inches.

The model must start without assistance.

Once an attempt is under way, the competitor may not touch it except to straighten its course if necessary.

Each entrant shall be allowed three attempts, the most number of reversals accomplished in any one attempt being the one
taken in consideration when deciding the winner.

The winner will be defined as the entrant whose model covers the greatest number of reversals on a level floor in one winding.

Proxy contestants are welcome.

The aim and rules are repeated here because they turned out to have a particularly unexpected influence on the result.

The track was a four foot long varnished wooden board set up with weighted Meccano boxes at each end. First off was Chris Shute Mk1.
This model went very fast and struck the end boxes with such enthusiasm that it kept knocking its track off line and had to be frequently corrected as allowed under Rule 6 In spite of this it managed thirty three and a bit traverses of the track on its first run. General opinion among the spectators inclined to the view that the winner had appeared already.

Subsequent models achieved up to 9 traverses - with one notable exception. This was Tim Edwards' entry which, on its first run did no less than fifty three (53) reversals. The success of this entry appeared to be down to three main features.

very careful engineering and construction

no reliance on gear driven reversing mechanism (crash gear changes caused some models to fail prematurely - i.e. when there was still spring power available).

no flexible drive band - the Magic Motor was coupled directly to the drive mechanism by a wheel pressing against the motor's drive pulley around which an elastic band had been wound.

Although the model travelled quite slowly (compared to the Shute rocket) it was quite heavy and so momentum ensured a clean direction change at each end of the course. Overall a total distance travelled of over 70 yards was a considerable achievement.

Complete results were as follows:

Name

First run

Second run

Chris Shute Mk1

33+

33+

Doug Carson

4

5+

Alan Blair

Withdrew

Tim Edwards

53

44+

Margaret Tattersfield

David Lawrence (no.3)

9

7

Bill Jack

3

Chris Shute Mk2

8+

8+

Robert Jones

Not counted (see below)

Two models gave rise to some concern regarding Rule 2. One of these (that of Bill Jack) contained a 5 1/2" strip of non-Meccano manufacture. The ends of the strip were not totally radiused. As the neither the strip itself, or the unusual shape of its ends was fundamental to the operation of the model this minor breach of the rules was allowed to pass. Concern was also raised regarding the unusual 1" spoked wheels on the David Lawrence model. These wheels which were Meccano having been included in one of the Crazy Inventor sets and being only suitable for tri-flat axles were clearly within the rules.

Robert Jones model on the other hand was disqualified. It was over 13" long and therefore clearly in breach of Rule 4. This was a considerable relief to the organisers as this unusual model did not cover the entire distance between the two end stops but instead oscillated back and forward with a period of about 1" The number of oscillations was never counted but probably amounted to over 100. When the Aim is examined it simply says "automatically reverse as many times as possible between a pair of obstacles 4 feet apart". It does not say that the vehicle has to cover the entire distance between the end stops or touch them - nor is there anything in the Rules to this effect. Had this vehicle not been in breach of Rule 4 it would have had to be declared the winner.

The losers in all of this were those responsible for making up the rules, who had better be prepared to take counsels opinion if they are to be employed for the purpose next year!

Pictures from Menstrie 2007

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REVERSING BLUES

by

Bill Jack

The recent competition at Menstrie produced some ingenious models. I was pleasantly surprised and indeed deeply humbled by efficacy of the entries and admired all of them. Many "thought" hours and physical hours must have gone into each one.

Mine started from scratch, as I had never built anything since my first Meccano was neglected when I was fourteen. It was lost, so I had to dig up bits of odd sets here and there to get going again. My final model was Mark 11 (eleven) having been built up and dismantled and reconfigured and rebuilt ten times. The motor was mounted here there and everywhere, inside and outside, and upside down, to try to get the best effect. Yet I still did not come up with the layout of many of the others, nor anything like the quality and only achieving three bumps. The main problem I found was with the gearbox which would reverse but required quite a dunt on the end to end control rod, to shift them and hold them in gear. I was at it on and off for many weeks and even enlisted the help of my colleague's mechanical knowledge and hoard of Meccano bits and pieces.

So, if ever the competition comes up again, hopefully I will have learned something from Menstrie. Meantime, roll on the next annual competition which presumably will be announced soon. Congratulations all round to the organisers and competitors